Drill sharpener



Feb. 20, 1945. w 0 BENNlNG 2,369,642

DRILL SHARPEI GER Filed June 8, 1942 v '2 Sheets-Sheet 1 Feb. 20, 1945.

w. 0. BE NN|NG 2,369,642

- DRILL SHARPENER 2 She ets-Sheet 2 v Filed'June 8, 1942 INVENTOR. firm-72024272712723,

Patented Feb. 20, 19 45 UNITED STATES. PATENT OFFICE Wilbert Orville Banning. Los Angeles, Calif. J Application June a, 1942, Serial No. 446,173

3 Claims. (01. 51-219) My invention relates to a drill sharpener, the

' primary object being to -provide effective means for quickly and accurately sharpening twist drills.

A further object is to provide a device of its 'is to provide a drill sharpener which is simple and inexpensive in construction and which is" readily adapted for use in grinding twist drills of various lengths and diameters, which is readily adjustable to regulate the angle and clearance at which the drill is sharpened, and the application of the. drill to the abrasive element longitudinally, which will not easily get out of order,

n'i'ain supporting base and is swung upon its pivot by hand, a suitable handle ll radiating from its periphery being provided. E is a supplemental support consisting of a table or plate resembling a segment superimposed above the turn table. ,This segment is pivoted about an axis formedby the pin 12, eccentric to the axis of the turn table so as toswing independently in the plane of and upon or about said table. An arcuate slot l3 near the periphery of and through the segment and a binding screw it Iiiand which is not subject to wear after long con- 7 tinuous use.

' To these ends, my invention comprises the features of construction and combination of parts hereinafter described and claimed.

In the accompanying drawing forming part of this specification, Fig. 1 is a side elevation of my improved drill sharpener, portions thereof being broken away; Fig. 2 is, a plan of the structure shown in Fig. 1; Fig. 3 is a side elevation of the drill holder separate from the device;-Fig.

4 is a plan of the drill holder; Fig. 5 is a front end elevation of the drill sharpener when the drill holder is in horizontal position; Fig. 6 is'an having its shank passing downwardly through said slot and threaded into the turn table serves to releasably fasten the segment in adjusted position circumferentially about its axis upon the surface of the turn table. A scale i5 inscribed in the surface of the turn table and a cooper ating pointer IS on the periphery of the segment serve to aid the operator in regulating the degree at which the segment is adjusted in a horizontal plane about its axis for the purpose to be hereinafter described.

I F is a pedestal mounted rigidly upon the supplemental supporting segment upon the upper end of which is tiltingly mounted to swing in a vertical plane a twist drill holder G. This holder has a body formed by a pair of parallel horizontally spaced flanges I] connected transversely end elevation of. the slide of the drill holder; Fig.

7 is a side elevation of a portion of the slide and the abutment shown in Fig. 6; Fig. 8 is a plan of the corresponding parts shownin Fig. '7; Fig. 9 is an end view of the cutting end of a twist drill such as is adapted to be sharpened by my improved drill grinder, and Fig. 10 is a diagram:. matic' plan illustrating the manner in which a twist drill is adapted to be sharpened by my improved drill sharpener. j

In the drawings. A is a flat base which may be i of any suitable shape upon which, as shown is an abrasive wheel 3 of usual type, revolved by the prime mover such as the electric motor indicated by C, the latter being mounted in 8- tionary position on the base and revolubly supporting the abrasive wheel, '.D is a turn-table revolubly mounted so a's to revolve in a horizontal plane on the'base about an axis formed by the pivot ii. The turn table functions as a nel opening horizontally and having a longitudiat their upper extremities by a longitudinal cradle l8, in which the twist drill such as H is adapted to be held with its cutting edge juxtaposed for sharpening against the work side surface of the rotatablev abrasive wheel B. Extending rearnal slide l9 above which the rearward body end of the shank of the drill extends freely from the supporting cradle. The flanges l1 straddle the upperend of the pedestal F and the drill holder tilts in a vertical plane on a horizontal shaft 20. An arcuate slot 2| through one of the flanges l1 and a binding screw 22 having its shank passing through said slot and threaded into the body of the pedestalserve to fasten the drill holder in vertically and forwardly inclined position to present the cutting edge of the drill to the work surface of the 'abrasive'wheel so as to sharpen the drill with the desired taper, A scale 23 inscribed on the surface of one of the flanges adjoining the fastener 22 and a cooperating vstaposition. i

The slide is, in cross section resembles a chanabove the slide has a pair. of bosses 33 nal toothed rack in its inner portion. Ar-

ranged to travel longitudinally-on the slide is anabutment I which functions as a back stop for resting the drill bitwith its cutting end juxtaposed to the abrasive work surface of the rotating abrasive wheel. This abutment resembles a. carriagev or collar closely conforming so as to slide freely longitudinally on the slide. The carriage holds a ratchet 26 which is pivoted at '21 between a pair of bosses 28 therein and has an inwardly extending toothed rack engaging end ting edge to produce the desired clearance. By adjusting the segment E about its eccentrically disposed axis l2, according to the scale [5, the

angle and .amount of clearance at which each surface 4| is ground is regulated. The adjustment of the parts of the device both m a vertical and horizontal plane can be easily and quick ly made to accommodate drills of a wide range 29 and a hand depressing arm 30 projecting out- Y wardly through an opening 3| in the carriage.

The rack engaging end 29 is pressed into en age- Y ment with the'rack teeth by the expansion spring 32. Normally the ratchet engages the rack to prevent rearward movement of the. abutment but when the operating arm is depressed the ratchet is disengagedand the abutment can be regulated as described in approximate adjustment along the slide. The upper side of the abutment and 34 cooperating with the body of the abutment to form a longitudinal bearing through which is threaded a longitudinal stop shaft 35. The inner end of this shaft has a swiveled bearing head 36 which presses against the end of the shank of the drill to form a back stop and adjustably sustain the drill with its cutting end coincident with the work surface of the abrasive element. A knurled barrel 3! in the abutment I and threaded on the back stop shaft provides a hand operable adjustment by the rotation of which said shaft can be regulated to rest the drill longitudinally.

The forward portion 38 of the back stop shaft is polygonal in cross section and slides in a corresponding passage in the forward'boss 34 to hold the shaft from turning when the adjusting barrel 3! is'revolved.

In use the drill to be sharpened is laid longitudinally in the cradle where it is held by hand with its work end to be sharpened adjusted to the work surface of the abrasive wheel and its shank sustained by the abutment a shown in Figs. 1 and 2. Two primary adjustments are provided by the structure which are apparent of sizes both in diameter and length.

The drill sharpener can be provided with any suitable abrasive wheel trimmer, such as J for trueing the work surface of the abrasive wheel from time to time when it becomes worn or ungvelnl, sag! trimmer being allowed to remain inc 1 e w en not in use by swingin own journal support 50. g d u'pon Its Operation When operating my improved drill sha the drill'holder G is first set at the desirer i sr i g l e in a vertical plane according to scale 23 to apply the cutting end of the drill in the holder to the side of the abrasive wheel B so as to sharpen the cutting edge 40 with the desired taper by the subsequent grinding operation. In this positlon the holder is secured by thebinding screw 22. The pedestal F is next set according. to a scale M5, to the desired clearance angle in which position it is secured by the binding screw M.

The twist drill such as H to b p e sharpene placed with its work end in the cradle I8 and ts shankextending rearwardly above the slide IS. The abutment I is next adjusted along the slide to an approximate position juxtaposed to the rearward end of the drill and w" stop 36 abutting the drill shank. 'Ih tv s i is then fed forwardly toward the side of the abrasive wheel by turning the 'adjustin barrel 31 until the drill contacts the abrasive wheel Both sides of the drillshould be cut with each advance of the twist drill towards the abrasive from the diagrammat c views shown in Figs. 9

and 10: first, for sharpening the opposite cut- ,ting edges 40 at the desired forward taper and,

second, for cutting the surfaces 4| back of the ing the drill over. While the drill is held in the cradle of the holder the abutment is adjusted with the head of the back stop shaft planted back of and against the rearward end of the shank of the drill so as to rest the drill longitudinally during' the entir'egrinding operation.

Following the grinding and sharpenin of each cutting edge of the drill at the desired taper the turn table D is swung slowly in its horizontal plane forwardly to the left about the pivot l0, causing the holder 'with the drill therein'to swing through an are H (see Fig. 10), horizontally and cut the end surface back of each cut-- drill by the abrasive element at the wheelto secure even results Ver Y l y light out desirable n order to secure the best results. 22:5;

arwdairgwstgp otfthe feed and forward out should e wi h a clearance cut b turn table to the left. y retain/Hg the The two cutting edges of the drill should in cline at the proper angle and at the same corresponding inclination to the longitudinal axisof the drill and should be of corresponding length.

The clearance angle is important as insufiicient' clearance causes splitting of drill web and excessive clearance weal re ri s t l i fe c 51 ting edge. The clearance of the surface following the cutting edges required also vari s ac cording to the character of material which is drilled. The adjustment ofthe clearance provided by the horizontal adjustment of the drill holder G on the rotatable table D enables the operator to provide the proper clearance by my improvement at which the drill'is sharpened In accordance with the patent statutes, I have 'described the principles of o peration of m n- .vention, together with the apparatu which ri ow consider-to represent the best embodiment thereof, but I desire to have it understood that the structure shown is only illustrative and that the invention can be carried out by other means and applied to uses other than those above set forth within the spirit of the invention and within the scope of the following claims.

Iclaim: l. A twist drill sharpener com prising, a be alium table journaled to revolve in a horizons; p ue uponsaid base, an abrasiveelement having a work surface in a plane normal to the turn table, a support journaled to revolve in a horizontal plane on the turn table about an axis eccentric to the'axis of the turn table and coincident with the work surface of the abrasive element, a drill holder freely tlltable to swing in a vertical plane upon said support and normally inclined downwardly toipresent the work end of a drill to the work surface of the abrasive element with its cutting surface within full view of the operator and cause the sharpening of the cutting edge of the drill at a forwardly tapering angle, means for holding the drill holder adjusted in tilted position so as to maintain a fixed angle at which the drill is cut, said turn table when rotated about its axis causing the abrasive surface of the abrasive element to cut the drill with a clearance surface back of the cutting edge thereof defined bythe eccentric position of the drill holding means on the turn table, and means for fastening said support adjust'ed in an are about its axis to establish the angle of clearance cut b the abrasive surface back of said cutting edge.

2. In a structure as defined in claim 1, the work' holder having a cradle disposed longitudinally for-holding a drill with its cutting end juxtaposed tothe work surface of the abrasive element, a rack extending longitudinally on the.

juxtaposed to said abrasive surface and hava ing a longitudinal rack, a carriage slidable longitudinally on the work holder in the vicinity of said rack, ratchet means on the carriage for releasably engaging the teeth of the rack and holding the carriage in selected longitudinal position on the work holder, and an adjustor on'. said carriage having micrometer precision for en- J gaging the rearward end of a drill and advancing the latter with its cutting end directed against the abrasive surface of the abrasive element.

WILBERT ORVIILE BENNING. 

